Multi-component exhaust gas sensors are needed to meet increasingly stringent government regulations. They are also needed for control of combustion performance and fuel economy. There is also a need for sensors that operate in other fluid streams, such as smoke stacks and other discharge media. However, presently available exhaust gas sensors are costly, consume a lot of power, and/or are often limited to sensing one component. Sensors are available that sense O2 or Nx, but are typically not able to sense gases like CO, CO2, or SO2. In addition, their high power consumption does not allow self-powered operation.
U.S. Patent Application No. 2004/0200900 to Hall discloses a sensing platform that can be used to accommodate new sensors and other electronics that Hall says are evolving so rapidly they are obsolete almost as they are developed. Paragraph 0169 suggests a thermopile, powered by a nuclear isotope. No specific mention of any self-powered sensor is made, nor is the idea of placing the platform in an exhaust system of a vehicle even possible.
U.S. Patent Application No. 2004/0226600 to Starer et al. operates a gas valve that is powered by a thermopile that derives heat from a pilot flame. The sensor does not seek to detect specific gases. U.S. Pat. No. 5,393,351 to Kinard et al. discloses a multilayer film multifunction thermal converter that uses thin films in combination with thermopiles and thermocouples. U.S. Pat. No. 5,576,251 to Garabedian et al. discloses a FET as a sensor but not for exhaust gases and not in combination with a thermopile for power or a transmitter for signal transmission.
Accordingly it would be of great advantage in the sensor art if a sensor could be provided that can measure all the various exhaust gas components.
Another advantage would be if a sensor could be developed that operates at sufficiently low power to be driven by a self-generated power source.
Yet another advantage would be to provide a sensor that would include self-diagnostics and self-calibration.
Still another advantage would be to provide a sensor that would operate with a wireless data transfer component.
Other advantages and features will appear hereinafter.